1. Field of the Invention
This invention relates to a method and apparatus for preparing a solid core fiber optic cable for a splice by applying a radial compressive strain to a waste end of the solid core fiber optic cable.
2. Description of Prior Art
Solid core fiber optic cable is commonly used to create a light source where light fixtures would be otherwise difficult to locate; to replace systems of multiple light bulbs; to reduce heat output at a light source; and/or many other practical and aesthetic applications. For instance, in the automotive industry, a single centralized light engine supplying light to a series of fiber optic cables can replace multiple light bulbs and fixtures by providing light to headlights, marker lights, runner lights, dome lights and instrument panels. As a result of the proliferation of fiber optic cable in such widespread applications, repairs, replacements and retrofits of fiber optic cable systems are often necessary. Therefore, an effective method and apparatus for creating a splice and maintaining a coupling between two ends of fiber optic cable, with minimum light loss, is necessary.
The Specification and Claims use the terms "solid core fiber optic cable" and "fiber optic cable" interchangeably. The method and apparatus of this invention are intended for use with fiber optic cable having an outer polymeric jacket and a light-transmitting inner core. Unlike fiber optic cable used for data communication that has a cross-section the size of a strand of hair, solid core fiber optic cable typically has a core diameter of between approximately 1 and 26 mm.
One such solid core fiber optic cable is Optiflex.TM. fiber optic cable made by Rohm and Haas of Philadelphia, Pa. Such fiber optic cable typically comprises three different materials: an acrylic copolymer inner core; a thin Teflon.TM. cladding used for reflection purposes; and a polyethylene outer jacket for protection. During the processing of the core, which in one embodiment is 7.1 mm in diameter, the cladding is extruded and joined with the inner core while in a molten state, thus providing a smooth interface between the inner core and the cladding. This smooth interface is beneficial to the transmission of light through the fiber optic cable for consistent reflection.
Fiber optic cable is currently cut or spliced using a hand tool having a spring biased Teflon.TM. coated razor blade. A guillotine-like action cuts through the outer jacket, the cladding and the inner core of the fiber optic cable resulting, at least initially, in a generally smooth inner core profile ready for a splice.
However, after the fiber optic cable is cut, for instance to prepare a splice between two lengths of fiber optic cable, the cladding and the inner core tend to delaminate and thus separate. This separation allows the inner core to relieve the residual tensile stresses imparted during the polymer curing process which results in a retracted, typically concave, inner core surface profile relative to the cladding and the outer jacket.
When two lengths of fiber optic cable having a retracted inner core surface profile are joined or spliced together, the result is an air gap between the opposing inner cores within the outer jackets. Such an air gap greatly reduces the effective light transmission through a spliced fiber optic cable. Mechanical fasteners exist that will hold and maintain a splice between two lengths of fiber optic cable, however, an effective method and apparatus to prepare a fiber optic cable for a splice is needed.